[utils] Utility functions from rocket-chip

tilelink/src/utils/OH1.scala

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+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2016-2017 SiFive, Inc. See LICENSE.SiFive for details
+
+package utils
+
+import chisel3._
+import chisel3.util.{Cat, OHToUInt}
+
+object OH1 {
+  def OH1ToOH(x: UInt): UInt =
+    ((x << 1).asUInt | 1.U) & (~Cat(0.U(1.W), x)).asUInt
+
+  def OH1ToUInt(x: UInt): UInt = OHToUInt(OH1ToOH(x))
+
+  def UIntToOH1(x: UInt, width: Int): UInt =
+    (~((-1).S(width.W).asUInt << x)(width - 1, 0)).asUInt
+
+  def UIntToOH1(x: UInt): UInt = UIntToOH1(x, (1 << x.getWidth) - 1)
+}

tilelink/src/utils/package.scala

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+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2016-2017 SiFive, Inc. See LICENSE.SiFive for details
+
+import chisel3._
+
+import scala.annotation.tailrec
+import scala.math.min
+
+package object utils {
+  // Fill 1s from low bits to high bits
+  def leftOR(x: UInt): UInt = leftOR(x, x.getWidth, x.getWidth)
+
+  def leftOR(x: UInt, width: Integer, cap: Integer = 999999): UInt = {
+    val stop = min(width, cap)
+
+    @tailrec
+    def helper(s: Int, x: UInt): UInt =
+      if (s >= stop) x else helper(s + s, x | (x << s)(width - 1, 0))
+
+    helper(1, x)(width - 1, 0)
+  }
+
+  // Fill 1s form high bits to low bits
+  def rightOR(x: UInt): UInt = rightOR(x, x.getWidth, x.getWidth)
+
+  def rightOR(x: UInt, width: Integer, cap: Integer = 999999): UInt = {
+    val stop = min(width, cap)
+
+    @tailrec
+    def helper(s: Int, x: UInt): UInt =
+      if (s >= stop) x else helper(s + s, x | (x >> s)(width - 1, 0))
+
+    helper(1, x)(width - 1, 0)
+  }
+}